PB2092: PRIMARY BONE DIFFUSE LARGE B CELL LYMPHOMA: A SINGLE CENTER EXPERIENCE
Authors: G. Abichou, M. Charfi, F. Kallel, Y. fakhfekh, L. Ghorbel, I. Saguem, W. Feki, H. Ben salah, T. Boudawara, Z. Mnif, J. Daoud, M. Elloumi
Journal: HemaSphere (2022)

Background: Primary bone lymphoma (PBL) is a rare disease and represents 5% of extranodal lymphomas and less than 2% of Non-Hodgkin Lymphomas. Primary bone diffuse large B-celllymphoma (PB-DLBCL) is the most common pathological type, comprising about 80% of PBL. This entity has a good prognosis and its treatment options are very limited, especially for elderly patients. Aims: The aim of this study is to describe characteristics of patients with PB-DLBCL and to assess the outcome of a cohort of patients in south of Tunisia. Methods: Our retrospective study involved all patients diagnosed with PB-DLBCL at the hematology department of Sfax between January 2008 and December 2019.We studied the diagnostic characteristics of these patients: age, sex andclinical features. The diagnosis was confirmed by histopathological examination according to the 2008 and the 2016 World Health Organization (WHO) classification of hematologic malignancies. Staging was estimated according to Ann Arbor system. Depending on the location of the lesion and skeletal radiographs, computed tomography (CT) scans and magnetic resonance imaging (MRI) were analyzed.We used the age adjusted International Prognostic Index (aaIPI) to evaluate the prognosis. Patients were treated with CHOP-like regimens with Rituximab when available. Autologous stem cell transplantation (ASCT) was indicated for patients aged 60 and younger with aaIPI>1. Radiotherapy was performed as a planned consolidation therapy after immunochemotherapy Kaplan Meier method was used to estimate overall survival and event-free survival Results: Twenty five patients with PB-DLBCL were identified during the study period. The mean age at diagnosis was 53,7 years (range 17-78). Sex ratio M/F was 1,5. The mean consultation delay was 3,8 months (1-12). The revealing symptom was bone pain in the majority of the cases (40%). B symptoms occurred in 19 cases (76%). Performans status was <=1 in 14 cases (56%). The most common tumor sites was the vertebrae (44%) followed by femur (12%), pelvis (12%) and rib cage (12%). Sixteen patients had elevated LDH (64%) and 2 patients had hypercalcemia at diagnosis. According to the Ann-Arbor classification, the stage of the disease was I in 5 patients (20%) and IV in 20 patients (80%). The aaIPI was > 1 in the majority of thes cases (64%). Three patients died before treatment (12%) and 22 patients received chemotherapy. Consolidative radiation therapy was administered in 36% of cases and ASCT was performed only in 3 patients. Complete remission was achieved in 8 patients (36%) and 3 patients were refractory to first-line chemotherapy (12%). Relapses were observed in 2 patients (8%) 2 and 12 months after completion of treatment. These 2 patients received platinum based salvage therapy and died from disease progression. With a median follow-up of 80 months (17-161), 5-year Overall survival and event-free survival were respectively 67% and 65%. Summary/Conclusion: PB-DLBCL is a rare disease. The non-specific initial presentation often leads to a late diagnosis. In our study, epidemiological and clinical characteristics were similar to the literature except for the stage of the disease, which was localized in 40-50% of the cases in the literature; this may be explained by the important consultation delay. Staging of the disease and response evaluation were not optimal due to non-availability of PET-CT and difficulty to realize MRI on time. Our CR rates were inferior to the literature (80-85%). EFS was inferior to those reported in other studies (70-100%) too. Radiotherapy and ASCT may improve our results.